The neuropathology core will coordinate the acquisition, processing, storage and distribution of autopsy material. Detailed histopathologic descriptions will form the foundation on which our allied research facilities can delineate the subtle differences in our clinically well characterized patient population. A clinical cohort consisting of 200 Alzheimer's patients, 100 patients with both Alzheimer's and Parkinsonian features, 50 non-demented Parkinsonian patients and 50 age-matched controls, all periodically evaluated with neuropsychological assessments, will ultimately form the bulk of our neuropathology specimens. The brains of patients suffering other rare dementing diseases of great scientific interest such as Pick's, Huntington's chorea, progressive supranuclear palsy, aged Down's Syndrome etc. will be evaluated when obtained. With an estimated mortality rate of 5-10%/year for patients with these diseases, we expect to collect approximately 20 brains/yr. and have 100 specimens at the end of five years. The protocol is compulsive and yet flexible so that it can be easily modified and/or expanded to incorporate additional patient groups, developing research techniques and evolving scientific questions.